Hydrostatic unit and its applications

ABSTRACT

A force feeder unit comprising a fixed body having two fluid orifices, mobile means mounted in said fixed body and defining a series of chambers of variable volume adapted to transfer a fluid along a cyclic path having a first region in which said chambers increase in volume and a second region in which said chambers decrease in volume, and a distribution means interposed in said fixed body between said orifices on the one hand and said chambers on the other, and comprising a first passage adapted to cause one of said orifices to communicate, at least in part, with the first region of said cyclic path and a second passage adapted to cause the other orifice to communicate, at least in part, with the second region of said cyclic path, said fixed body further comprising at least a third orifice, and said distribution means comprising at least a third passage adapted to cause said third orifice to communicate with at least the first region of the cyclic path of said chambers at which the chambers increase in volume, so that said unit has at least two input flows and one output flow.

United States Patent [191 Lepelletier HYDROSTATIC UNIT AND ITS APPLICATIONS [75] Inventor: Pierre Andre Georges Lepelletier, Chatou, France [73] Assignee: Societe Anonyme Francaise Du Femdo, Paris, France [22] Filed: Aug. 1, 1972 [211 App]. No.: 277,113

[30] Foreign Application Priority Data Aug. ll, 197i France 71.29305 [52] US. Cl. 418/61 [51] Int. Cl. F014: [I02 [58] Field of Search 418/61 A, 61 B [56] References Cited UNITED STATES PATENTS 3,549,l l0 l2/l970 Cotton 4l8/6l A 3,584,985 6/l97l Baatrup 418/61 B Primary Examiner-C. J. Husar Attorney, Agent, or FirmYoung & Thompson [451 Feb. 1 1, 1975 [57] ABSTRACT A force feeder unit comprising a fixed body having two fluid orifices, mobile means mounted in said fixed body and defining a series of chambers of variable volume adapted to transfer a fluid along a cyclic path having a first region in which said chambers increase in volume and a second region in which said chambers decrease in volume, and a distribution means interposed in said fixed body between said orifices on the one hand and said chambers on the other, and comprising a first passage adapted to cause one of said orifices to communicate, at least in part, with the first region of said cyclic path and a second passage adapted to cause the other orifice to communicate, at least in part, with the second region of said cyclic path, said fixed body further comprising at least a third orifice, and said distribution means comprising at least a third passage adapted to cause said third orifice to communicate with at least the first region of the cyclic path of said chambers at which the chambers increase in volume, so that said unit has at least two input flows and one output flow.

SHEET 1 OF 3 FRJENYEU FEB] 1 5 PATE FEBI 1 1925 SHEET 2 OF 3 1 HYDIRGSTATIC UNIT AND ITS APPLICATIONS The present invention relates to a hydrostatic unit, eg a force feeder unit, of the general type comprising a fixed body having two fluid orifices, mobile means mounted in the fixed body and defining a series of chambers of variable volume which, in operation, transfer the fluid along a cyclic path having a first region in which the chambers increase in volume and a second region in which they decrease in volume, and a distribution means interposed in the fixed body between the said orifices on the one hand and the said chambers on the other, and comprising a first passage causing one of the orifices to communicate at least in part with the first region of the cyclic path and a second passage causing the other orifice to communicate, at least in part, with the second region of the cyclic path.

The mobile means may be of any appropriate type for example with a double rotor, with axial pistons, with radial pistons, etc. The distribution means may be either fixed or angularly movable, and the unit may have a constant or variable cylinder capacity.

In general, a hydrostatic unit is utilized, either as a motor, the mobile means being receivers and being driven by a working pressure, or as a pump, the mobile means being transmitters and maintaining a delivery pressure. In present day applications, especially for speed-changing devices, a hydrostatic unit forming a motor is frequently associated with another hydrostatic unit forming a pump.

The present invention has for its object a hydrostatic unit which is arranged so as to operate by itself simultaneously as a motor and a pump, in such manner as to induce, under the impulsion of a flow from one of the orifices to the other, at least one supplementary flow for the purpose of adding together at least two flowrates and/or of dividing at least one flow rate into two or more fractions in a manner which is automatically modulated as a function of the conditions of volume and pressure.

A hydrostatic unit according to the invention is characterized in that the fixed body comprises at least one third orifice and in that the distribution means comprises at least one third passage causing the said third orifice to communicate with at least the region of the cyclic path in which the chambers increase in volume, so that the unit has at least two input flows and one output flow.

The difference in pressure which is applied between the first two orifices tends to move the mobile means. From then on, a flow takes place from one of the first two orifices to the other and at the same time an addi tional flow is induced by the third orifice.

In the hydrostatic unit according to the invention, the mobile means are left free in movement and, as has already been indicated above, they simultaneously play a part of reception and emission by modulating the flow-rates and pressures at the inputs and outputs.

A hydrostatic unit according to the invention may receive numerous applications and, amongst others, especially as a toppingup" or filling-up device, that is, as a force felder unit, or as an anti-cavitation protection means for a hydraulic installation. In this case, the first two orifices are coupled to two conduit systems respectively at high and low pressure, while the third orifice is coupled to a tank. A filling-up device of this kind has the advantage of being very effective, of being capable of convenient connection on any existing installation and of causing neither disturbance nor any substantial fall in efficiency of the installation.

A hydrostatic unit in accordance with the invention may also serve, inter alia, to distribute the energy from at least two hydraulic power stations between two or more utilizing services, this being effected as a function of the conditions of pressure.

Forms of construction will be described below by way of examples, reference being made to the accompanying drawings, in which:

FIG. 1 is a view of a hydrostatic unit according to the invention in longitudinal section, taken along the chain-dotted line [-1 of FIG. 2;

FIG. 2 is a corresponding view in transverse section, taken along the line II-II of FIG. 1;

FIG. 3 is a diagram of a hydraulic installation comprising the hydrostatic unit shown in FIGS. 1 and 2;

FIG. 4 is a view in transverse section of an alternative form of the hydrostatic unit;

FIG. 5 is a diagram of a hydraulic installation comprising an alternative form of the hydrostatic unit shown in FIG. 4;

FIG. 6 is a diagrammatic illustration of another alternative form.

Reference will first be made to FIGS. 1 to 3. A hydrostatic unit according to the invention comprises a fixed body 10 and mobile means 11 and 12. The body 10 is composed, in the example shown, of two shells 10a and 10b, between which is arranged a ring 10c. The mobile means 11, 12, are mounted between the shells 10a and 10b and are surrounded by the ring 100.

In the example shown, the mobile means ll, 12 comprise two rotating members or rotors I1 and I2. The rotors 11 and 12 have working portions shaped like scallops l3 and 14 engaged one with the other.

The peripheral rotor 11 is rotatably engaged inside the ring 10c and has an axis of rotation A. The central rotor 12 is rotatably mounted on a short shaft 15 engaged in rings 16a and 16b of the shells 10a and 10b of the fixed body 10, and has an axis of rotation B which is displaced with respect to the axis A.

The peripheral rotor 11 is provided with one scallop more than the central rotor 12. The scallops l3 and 14 of the rotors 11 and 12 define chambers 17 which are displaced along a cyclic path during the course of the rotation of the rotors l1 and 12. The chambers 17 have a volume which varies during the course of their displacement.

With a rotation in the direction of the hands of a watch, (arrow F of FIG. 2) the chambers 17 increase in a volume on the right-hand side of FIG. 2, that is to say on the right-hand side of the central plane M passing through the axes A and B, and decreasing in volume of the left-hand half of FIG. 2, that is to say on the lefthand side of the plane M.

The fixed body 10 comprises a first orifice 18 forming a suction orifice and a second orifice 19 forming a delivery orifice. A distribution means is provided in the body 10 and is interposed between the orifices 18 and 19 on the one hand, and the chambers 17 on the other. This distribution means comprises a first passage 20 which causes the orifice 18 to communicate, at least in part, with the right-hand region of the cyclic path of the chambers 17, and a second passage 21 which causes the orifice 19 to communicate, at least in part, with the left-hand region of the cyclic path of the chambers 17.

The passages 20 and 21 are isolated from each other by separating partitions known as commutation zones, indicated by the references 22 and 23 of FIG. 3.

In the example shown, the distribution means is formed directly in the mass of the shell b of the body 10, but it may also be made angularly displaceable in such manner that it is possible to regulate the position of the plane of commutation passing through the zones 22 and 23 with respect to the central plane M, this having the object of modifying the swept volume of the hydrostatic unit. To this end, it would only be necessary to provide in the shell 10b an angularly displaceable portion arranged for example on the left-hand side of the chain-dotted line 1011 in FIG. 1.

In operation, fluid is discharged from the suction orifice 18 towards the delivery orifice 19 through the intermediary of the first passage of the chambers 17 and of the second passage 19.

According to the invention, the fixed body 10 comprises at least a third orifice while the fixed or adjustable distribution means consisting of the passages 20 and 21, also comprises at least a third passage 24; This latter causes the orifice 25 to communicate with at least one region of the cyclic path of the chambers 17.

In the example shown, in which there is one single passage 24 and also one single passage 25, there is also only one single region, located on the right-hand side of the central plane M, that is to say on the suction side.

The third passage 24 is placed after the passage 21 and before the passage 20, in the direction of the arrow F.

It is isolated from the passages 20 and 21 by separating partitions known as commutation zones 23 and 123.

An application of the hydrostatic unit shown in FIGS. 1 and 2 is illustrated in FIG. 3, in which this hydrostatic unit plays the part of a topping-up or re-filling device, that is, a force feeder unit associated with a hydraulic station 26, the shaft 15 being left free for rotation.

The hydraulic station 26 comprises fluid pressure means such as a pump and/or an accumulator. The station 26 is connected on the one hand to a high-pressure conduit 27 in which the fluid-pressure means deliver the fluid at high pressure, and on the other hand to a low-pressure conduit 28 from which the fluid-pressure means derive their suction. There is shown at 29 a conduit which is coupled to the station 26 so as to collect all the leakages from the station and bring them into a tank 30.

The fluid pressure is directed towards utilization means 126, of which there is seen at 129 the conduit intended to collect the leakages and to bring them to the tank 30. i

With a view to the use of the hydrostatic unit of FIGS. 1 and 2 as a re-filling device associated with the station 26, the shaft 15 is left free for rotation, the suction orifice 18 is connected by a conduit 31 to the highpressure conduit 27, the delivery orifice 19 is connected by a conduit 32 to the low-pressure conduit 28, and the third orifice 25, associated with the third passage 24, is connected by a conduit 33 to the tank from which this conduit sucks its fluid in accordance with the topping-uprequirements of the station 26.

These topping-up requirements are conditioned simultaneously by the hydraulic losses of the station 26 and by the losses of the ultilization means 126, such as normal routine leakages or accidental leakages which may be the cause of cavitation phenomena in the station 26 or in the utilization means 126.

Amongst the chambers 17 located on the right-hand side of the plane M, some are exposed to the high pressure of the conduit 27 through 31, 18, 20, whilst certain others are exposed to the pressure (generally, but not necessarily zero pressure) of the tank 30 through 33, 25 and 24. With regard to the chambers 17 located on the left-hand side of the plane M, these are only exposed to the low pressure of the conduit 28, through 32, 19 and 21.

The difference in pressure at 20 and 21 has a driving effect which causes the rotors 11 and 12 to rotate in the direction in which the chambers carry out their cyclic path in the direction of the arrow F. The chambers 17 are thus permitted to transfer, on the one hand a driving flow from 20 to 21 and on the other hand an induced flow from 24 to 21.

It is this induced flow which ensures the topping-up of the station 26. It will be observed that the hydrostatic unit ensures a close following of the pressures at 31 and 32, that is to say at 27 and 28, and that the speed of rotation of the rotors 11 and 12 is a fuction of the ratio of the flow rates at 31 and 32, that is to say of the real topping-up requirements of the whole of the installation 26, 126.

More particularly, the hydrostatic unit according to the invention permits an automatic modulation of the flow rates and pressures as a function of each other, taking into account the two following relations:

Q32 Q31 Q33 ar as) Q31 32 as) Q32 in which Q and P designate respectively the flowrate and the pressure in the conduit 31, Q and P designate respectively the flow-rate and the pressure in the conduit 33, and Q and P designate respectively the flow-rate and the pressure in the conduit 32.

The relation (1) concerns the conservation of the flow-rates and the relation (2) deals with the conservation of energy.

In the event of abnormal increase in the fluid losse for example due to an accidental fracture of a conduit, the flow-rate at 32 increases and tends to compensate for these losses by playing the part of a protection device for the station 26 and the utilization means 126 which prevents or considerably reduces the phenomena of cavitation.

Generally speaking, the hydrostatic unit may thus be utilized as a protection device for any hydraulic installation such as the station 26 or any other installation of any kind.

It will be appreciated that the hydrostatic unit which has just been described has a speed of rotation which is automatically controlled in dependence on the topping-up requirements. It does not therefore reduce the power available at the level of the station 26, contrary to the usual topping-up pumps which have a fixed speed of rotation and can send back to the tank through a discharge valve, substantial quantities of fluid which reduce the efficiency.

It will also be appreciated that this same hydrostatic unit may conveniently be connected to the most judiciously chosen points on any existing installation, and is not necessarily mechanically coupled to the station 26 only, for which it constitutes a heavy burden of 5 weight, cost and space occupied.

It will be noted that the device described with reference to FIGS. 1 to 3 fulfills its purpose on condition that the operation of the station 26 always continues in the same direction, high pressure at 27 and low pressure at 28, and is not permitted to reverse.

In certain applications, the station 26 may be allowed to send the high pressure either into the conduit 27 or into the conduit 28. It is then advantageous that the hydrostatic unit ensures the topping-up in both cases.

In FIG. 3, therefore, it will be evident that a topping up or filling up unit, that is, a force feeder unit, is provided in which liquid flows in through conduit 31 and out through conduit 32, and is augmented through conduit 33 from an associated reservoir 30. The unit thus is adapted to top from this reservoir and thereby to direct to conduit 32 a quantity of liquid which is in addition to the quantity of liquid in conduit 31. In this way, liquid leakages and losses are compensated by force feeding, and cavitation is avoided.

The use of force feeders in the art to protect such devices is well known and need not be further elucidated. These may, for example, be of the nature of the positive displacement geartype replenishing and cooling pump shown in U.S. Pat. No. 3,465,520, Sept. 9, 1969. The novelty of the present invention resides in the particular structure of the force feeder unit per se, whereby the flow rates and pressures are automatically modulated as a function of each other as explained above in connection with the empirical formulae.

Reference will now be made to FIGS. 4 and 5, in which such a hydrostatic unit is shown. The arrangement is similar to that which has been described with reference to FIGS. 1 to 3, and there is recognised in FIG. 5 at 20' and 24 the passages located on the righthand side of the plane M, but the passage 21 is replaced by two separate passages 40 and 41 which are symmetrical with the passages 20' and 24'. In this case there are therefore not three but four passages in the distribution means. It will be noted that the first and second passages 20' and 40 are of smaller capacity than the third and fourth passages 24' and 41.

The passage 20' is connected by a conduit 31 to the conduit 27 and the passage 40 is connected by a conduit 32' to the conduit 28'. The passages 24' and 41 are connected to the conduit 33 of the tank 30 by two non-return valves 42 and 43. Advantageously, a suction filter 44 is inserted in this conduit 33 for the purpose of filtering the working fluid. The passage 41 is connected to the passage 40 by a non-return valve 45 and the passage 24' is connected to the passage 20' by a non-return valve 46.

When the conduit 27' plays the part of a highpressure conduit and the conduit 28 acts as a lowpressure conduit, the fluid circulates and the rotors rotate in the direction indicated by the arrows in full lines, the valves 42 and 45 being opened and the valves 43 and 46 being closed by the effect of the differences in pressure previously referred to.

When the conduit 28' plays the part of a highpressure conduit and the conduit 27 acts as a lowpressure conduit, the fluid circulates and the rotors rotate in the direction indicated by the arrows in broken lines, the valves 43 and 46 being open and the valves 42 and 45 being closed.

In both cases, the operation is similar to that which has already been described with reference to FIGS. 1 to 3, which ensures the topping-up and the protection of the hydraulic installation.

As can more particularly be seen from FIG. 4, the clapper-valves 42, 43, 45 and 46 are advantageously incorporated in the body of the hydrostatic unit. This body 10 has three orifices, l8, l9 and 25.

In the example of FIGS. 1 to 3, the third passage 24 acting as a supplement to the suction passage and to the delivery passage, is arranged on the suction side, and this is also the case in the example of FIGS. 4 and 5, in each of the two directions of operation in which only that of the supplementary passages which is located on the suction side plays the part of that of FIGS. 1 to 3.

The hydrostatic unit thus arranged permits an addition of two or more flow-rates (that at 31 and that at 33 which are added together at 32 in FIG. 3).

The hydrostatic unit according to the invention may also be arranged in such manner as to receive two or more inputs and to deliver two or more output flowrates.

To this end, as shown in FIG. 6, in addition to the first passage 20" forming a suction passage and the second passage 21" forming a delivery passage, there is provided a third passage 24a on the suction side and a fourth passage 24b on the delivery side.

20passage 29" is connected by a conduit 60 to a hydraulic station 61. The passage 24a is connected by a conduit 62 to another hydraulic station 63'. The passage 21' is connected by a conduit 64 to a utilization service 65. The passage 24b is connected by a conduit 66 to another utilization service 67.

In this case, the hydrostatic unit collects together the flow-rates at 60 and 62 and divides the sum at 64 and 66. It automatically modulates the collection and the division of the output pressures as a function of the input pressures.

In the various forms of embodiment which have been described up to the present, the shaft 15 is left to be free in rotation. It may also be envisaged to apply mechanically to the shaft 15 a driving torque or a resistive torque with a view to obtain a supplementary effect.

There have been shown more particularly the mobile means defining a series of chambers of variable volume and with a cyclic travel, in the form of rotors l1 and 12 with scallops l3 and 14 constituting two moving parts only and very simple, but it will be understood that the hydrostatic unit according to the invention may not only be of this type but also of any other appropriate type, for example the type with axial pistons, with radial pistons, of the type with blades, rollers, elastic diaphragms, etc.

What I claim is:

1. In the combination of a force feeder unit having a fluid conduit to supply liquid to said unit and a fluid conduit to remove liquid from said unit and a reservoir and means for supplying from said reservoir to said unit a quantity of liquid additional to the liquid from said one conduit, said unit comprising a fixed body having orifices connected with said conduits; the improvement comprising mobile means mounted in said fixed body and defining in said fixed body a series of chambers of variable volume adapted to transfer said liquid along a cyclic path having a first region in which said chambers increase in volume, and a second region in which said chambers decrease in volume, and distribution means disposed in said fixed body between said orifices on the one hand and said chambers on the other hand, said distribution means comprising means defining a first passage through which one of said orifices communicates with said first region, and means defining a second passage through which another of said orifices communicates with said second region, said fixed body having a third orifice connected with said supplying means from said reservoir, said distribution means comprising means defining a third passage through which said third orifice communicates with at least said first region in which said chambers increase in volume.

2. A combination as claimed in claim 1, and means defining a fourth passage in said fixed body, said fourth passage communicating with a region of said path in which said chambers diminish in volume, non-return valve means for coupling together said second and fourth passages on the one hand and said first and third passages on the other hand, said non-return valve means permitting respectively the establishment of liquid circulation in the direction of said fourth passage ,toward said second passage and in said third passage toward said first passage.

3. A combination as claimed in claim 2, said nonreturn valve means being disposed in said body.

4. A combination as claimed in claim 2, having a first conduit system under high pressure and a second conduit system under low pressure and means for reversing said high and low pressures with respect to said conduit systems, means connecting said first and second passages respectively to said conduit systems, means connecting said third passage through said non-return valve means to a tank, and means connecting said fourth passage through said non-return valve means to said tank.

5. A combination as claimed in claim 4, said first and second passages being symmetrical with each other, said third and fourth passages also being symmetrical with each other.

6. A combination as claimed in claim 1, in which said mobile means are mounted so as to be freely movable inside said fixed body.

7. A combination as claimed in claim 1, having a high pressure conduit system and a low pressure conduit system, one of said liquid input flows into said unit being derived from said high pressure conduit system, the other liquid input flow into each said unit being taken from a tank, said liquid output flow from said unit entering said low pressure conduit system.

8. A combination as claimed in claim 1, and means defining a fourth passage in said body, said fourth passage communicating with a region of said cyclic path in which said chambers diminish in volume whereby said unit has at least two input flows and two output flows. 

1. In the combination of a force feeder unit having a fluid conduit to supply liquid to said unit and a fluid conduit to remove liquid from said unit and a reservoir and means for supplying from said reservoir to said unit a quantity of liquid additional to the liquid from said one conduit, said unit comprising a fixed body having orifices connected with said conduits; the improvement comprising mobile means mounted in said fixed body and defining in said fixed body a series of chambers of variable volume adapted to transfer said liquid along a cyclic path having a first region in which said chambers increase in volume, and a second region in which said chambers decrease in volume, and distribution means disposed in said fixed body between said orifices on the one hand and said chambers on the other hand, said distribution means comprising means defining a first passage through which one of said orifices communicates with said first region, and means defining a second passage through which another of said orifices communicates with said second region, said fixed body having a third orifice connected with said supplying means from said reservoir, said distribution means comprising means defining a third passage through which said third orifice communicates with at least said first region in which said chambers increase in volume.
 2. A combination as claimed in claim 1, and means defining a fourth passage in said fixed body, said fourth passage communicating with a region of said path in which said chambers diminish in volume, non-return valve means for coupling together said second and fourth passages on the one hand and said first and third passages on the other hand, said non-return valve means permitting respectively the establishment of liquid circulation in the direction of said fourth passage toward said second passage and in said third passage toward said first passage.
 3. A combination as claimed in claim 2, said non-return valve means being disposed in said body.
 4. A combination as claimed in claim 2, having a first conduit system under high pressure and a second conduit system under low pressure and means for reversing said high and low pressures with respect to said conduit systems, means connecting said first and second passages respectively to said conduit systems, means connecting said third passage through said non-return valve means to a tank, and means connecting said fourth passage through said non-return valve means to said tank.
 5. A combination as claimed in claim 4, said first and second passages being symmetrical with each other, said third and fourth passages also being symmetrical with each other.
 6. A combination as claimed in claim 1, in which said mobile means are mounted so as to be freely movable inside said fixed body.
 7. A combination as claimed in claim 1, having a high pressure conduit system and a low pressure conduit system, one of said liquid input flows into said unit being derived from said high pressure conduit system, the other liquid input flow into each said unit being taken from a tank, said liquid output flow from said unit entering said low pressure conduit system.
 8. A combination as claimed in claim 1, and means defining a fourth passage in said body, said fourth passage communicating with a region of said cyclic path in which said chambers diminish in volume whereby said unit has at least two input flows and two output flows. 